1. Field of the Invention
The present invention relates to an improvement in a throttle grip position maintaining device in an outboard engine system, which is mounted between a bar handle for steering the outboard engine system and a throttle grip rotatably but axially non-movably fitted over the bar handle for controlling the opening degree of a throttle valve of an engine, thereby providing a frictional resistance to the throttle grip to retain the throttle grip at any opening degree of the throttle valve.
2. Description of the Related Art
In such a throttle grip position maintaining device in an outboard engine system, if the frictional resistance provided to the throttle grip is too large, an operating load on the throttle grip is also too large, thereby deteriorating the lightness of the throttle control. On the other hand, if the frictional resistance is too small, a retaining force applied to the throttle grip is also too small and for this reason, the throttle grip is liable to be moved from the position corresponding to a desired opening degree of the throttle valve. Therefore, a throttle grip opening degree maintaining device has been proposed, which is designed so that the frictional resistance is made variable to enable the regulation of the retaining force for a throttle grip, as disclosed in Japanese Patent Application Laid-open No.6-144379.
In the device disclosed in the above Patent, a ring nut is threadedly fitted over the throttle grip, and a friction member is interposed between the ring nut and a step of a bar handle opposed. to an end face of the ring nut, whereby the retaining force for the throttle grip is regulated by regulating the amount of tightening of the ring nut relative to the friction member.
In such throttle grip position maintaining device, however, when the ring nut is, for example, tightened to press the friction member, a thrust load directed to an outer end of the bar handle is applied to the throttle grip due to a reaction of the pressure. When the throttle grip is displaced axially by the thrust load, a variation in opening degree of a throttle valve of an engine is undesirably generated.
The present invention has been achieved with the above circumstances in view, and it is an object of the present invention to provide a throttle grip position maintaining device of the above-described type in an outboard engine system, wherein even when the retaining force for the throttle grip is regulated, the thrust load is not applied to the throttle grip and moreover, the retaining force can be maintained stably after the regulation.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a throttle grip position maintaining device in an outboard engine system, which is mounted between a bar handle for steering the outboard engine system and a throttle grip rotatably but axially non-movably fitted over the bar handle for controlling the opening degree of a throttle valve of an engine, thereby providing a frictional resistance to the throttle grip to retain the throttle grip at a position corresponding to any opening degree of the throttle valve. The throttle grip position maintaining device comprises a retained portion which is integrally formed on the throttle grip, a friction member axially superposed on the retained portion, a support member disposed on axially one side of the retained portion and the friction member and axially slidably but non-rotatably mounted to the bar handle, a regulating member threadedly fitted over the support member and having an urging portion disposed on the axially other side of the retained portion and the friction member, and an anti-loosening means provided between the support member and the regulating member for inhibiting the disorderly movement of the regulating member, the friction member being non-rotatably connected relative to one of the retained portion and the support member, but being rotatably connected relative to the other of the retained portion and the support member.
The retained portion and the urging portion correspond to an outward-facing flange 31 and an inward-facing flange 34 respectively in an embodiment of the present invention, which will be described hereinafter.
With the first feature, when the regulating member is tightened relative to the support member, both the support member and the regulating member are displaced axially, to axially clamp the friction member and the retained portion of the throttle grip, thereby providing a desired frictional resistance to the retained portion between the support member and the regulating member. Thus, the throttle grip can be retained at a position corresponding to any opening degree of the throttle valve, while avoiding that a thrust load is applied to the throttle grip.
Moreover, the disorderly movement of the regulating member is inhibited by the anti-loosening means and hence, the regulated retaining force for the throttle grip can be maintained stably, to contribute to an enhancement in steerability of the outboard engine system.
According to a second aspect and feature of the present invention, in addition to the first feature, the anti-loosing means comprises a click stop mechanism designed to provide a sense of moderation to a user, whenever the regulating member is rotated through a given angle.
With the second feature, it is possible for the user to accurately sense an angle of rotation of the regulating means, i.e., the retaining force for the throttle grip.
According to a third aspect and feature of the present invention, in addition to the second feature, the click stop mechanism comprises a plurality of first protrusions projectingly provided on an outer peripheral surface of the support member and arranged at circumferentially equal distances, and a plurality of second protrusions projectingly provided on an inner peripheral surface of the regulating member surrounding the plurality of the first protrusions and arranged at circumferentially equal distances, whereby some of the second protrusions are elastically brought into or out of engagement with some of the first protrusions, whenever the regulating member is rotated through a given angle.
With the third feature, the click stop mechanism comprises the plurality of first protrusions and the plurality of second projections and hence, is extremely simple in construction and can be provided at a low cost.
According to a fourth aspect and feature of the present invention, in addition to the third feature, the numbers of the first and second protrusions are different from each other, and the circumferential widths of the first and second protrusions are also different from each other, whereby some of the first protrusions and some of the second protrusions are in elastic engagement with each other in any rotated position of the regulating member.
With the fourth feature, it is possible to easily set a given angle of the regulating member, thereby providing a sense of moderation to a user.
The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.